Puffed wheat and method of making same



Patented Sept. 22, 1953 NITED STAT TENT QFF ICE PUFFED. WHEAT ANDMETHOD. OF MAKING SAME No Drawing; ApplicationlJune 12, 1953,

Serial No. 361,411

15' Glaims; 1,

This invention relates to" a; puffed cereal and method of preparingsame, and particularly'to puffed wheat;

Thepresent application is a continuation-inpart of my copendingapplication, Serial No. 296,963; filed July'2, 1952, nowabandoned, whichin turn is a continuation-in-part of my applications, Serial No; 40,630filed July 24, 194:8, now abandoned, and copending Serial No. 189;679;filed October 11', 1950', now abandoned. My application; Serial No; 189,679", filed October 11, 1950,- was a continuation-in-part of myfollowing applications: Serial No. 34,821, now abandoned; Serial No.34,822 now abandoned; and Serial No; 34-3823; now-abandoned, all filedJuly 23; 1948; Serial No. 231869, filed April 28, 1948, now abandoned;SerialiNo. 38;l79; filed July 10, 1948'; now abandoned; and Serial No.40,636, filed July 24, 1948; now abandoned.

Reference is had to the related cases of John M: Beer and Frank B.Doyle, Serial No. 62,984, filed December 1, 1948; Allison and Carman,Serial No. 1 615744, filed May 12; 1958; now abandoned Carman. andAllison, Serial No. 259,313, filed November 30; 1951, now abandoned; andGar-man and Allison, Serial No. 275,458, filed March 7; 1952, nowabandoned.

The-problem" ofpuflihg organic cellular mate'- riai" such as wheatinvolves a large number of interlocking variables. as'will trapexpanding gas andthus provide the pressure differential necessary forpuffing. A suddendrop in pressure must be provided'of such amountto'produce-thepressure difference necessaryno't only'to expand the cellwalls-but to do so; in spite of theleakage that necessarily occurs. Onthe other hand, thepressure difference must be great enough to exceedthe elastic limit ofthe" material before puffing has occurred. The

expansibility" oi the cell wall normally depends upon the moisturecontent of the product, the condition oi that moisture as to being freeor combined, thetemperature of the article and-its chemical condition;particularly as to-wh'ether it itco'olied or uncookedi Likewise,there-must not only be the pressure diiierencerequired to institutepufiihg, but there must bear volumetric increase of the gases in-VOIVB'Q sun'icientto maintain it.

l? have now found that anotl'ier factor involved, which'hashitherto'been completely overlooked but; the accomplishment of which isinherent in theopera-tion described in my previous applications referredto, is that once'tlie wheat has been puff-ed; the puffed condition must"be The wheat cells are such maintained even afterv the pressure"difference has been removed. One of the difiiculties encountered" inmany instances. of: puifing in the prior art was that the wheat could bepuffed; but after puffi'n'g would collapse because of'the weakenedcondition of the walls following the leakage out of the gas which.produced puffing. This was particularly trueif, after puffing; thepressure outside: of the: puffed wheat wasincreased.

I have now found that by suddenly cooling and dehydrating the product?so that its final temperature is below 150'F. and preferably well belowF.as2 for example,. from. 32 F. or

' lower up to, say, 100 thatithe' cell. walls. of

the product on puffing are cold set so that on standing or on theapplication of pressure, even of a greatly increased amount, collapsedoes not occur.

These results are obtained. automatically by following the proceduresalready outlinedin my previous applications. In these procedures, thefollowing'points-are'important':

l. Substantially all of the air should be removed from the product andreplaced'byan atmosphere-of steam prior to pufiing.

2. The product should'be cooked or moistened by steam or otherwise,preferably by the addition of substantially air-free steam at higherpressure and temperature until the condition of the material is properfor pufling and its moisture' content is within the desired range. Theuse. of theprocess permits the introduction of substantially-moremoisture than waspermissible under the old processes.

3. It is preferred that thesudden release of pressure be into amaintained vacuum zone which is initially'below 8 inches of mercuryabsolute. The conditions of the resulting explosion should be such as tocause" cold setting of the puffed wheat. This means that in actualpractice, employing commerciallypracticable vacuum equipment, thepressure may ride up somewhat during the puffing step. It" is preferredto continue evacuation of the vacuumzone during the pufiing'step so asto cause cold setting of the pu-fied-- wheat. Theexpansion. of air-freesteam into a vacuum of 4 inches of mercury absolute will automaticallyreduce the temperatureof the product to approximately F. 1 Reduction ofthe pressureto-Z inches reduces the temperature approximately to- 100 F.Reduction to 1 inch reduces it to about." 79- F. and reduction to-0.2inch reduces it toapproximately 3r F- Furthermore; by pufiing into amaintained vacuum, it is possible to obtain a greater temperature dropin number of degrees between the maximum and minimum than was ordinarilyobtainable heretofore. The result of this greater temperature drop wasto permit the evaporation of more water from the product by boiling intosteam. This boiling not only maintained the pressure difference forpufiing, but the removal of the water helped to cold set the cell wallsby reducing plasticity and elasticity. The combination of the moisturereduction plus chilling, particularly below 100 F., has produced resultsnot heretofore obtainable.

In a vacuum process, this reduction of temperature is of particularsignificance, since the lower the vacuum used the greater is theincrease in pressure after the completion of the puffing operation whenthe material is taken back into the atmosphere. If it were not for thecooling and drying eifects, many products would not be able to maintaintheir puffed condition when the pressure is increased, for example from2 inches absolute to 30 inches absolute-an increase of fifteenfold.

The removal of the air from inside the wheat grains in the firstinstance has a number of advantages. In the first place, the oxygen ofthe air has a deleterious effect on the wheat grains, particularly whenthey are heated. Secondly, the removal of non-condensable gasesincreases the permeability of the wheat grains to heat and to steam sothat heating will occur uniformly and the steam will penetrate equallyto all portions of the wheat grains.

Thus, when it comes to introducing steam for increasing the moisturecontent of the product and for cooking it to the necessary chemical andphysical conditions, the fact that air is not present inside the wheatgrains produces a rapidity and uniformity of steaming and cooking nototherwise possible. Because of this greater uniformity and speed, it ispossible to go to higher temperatures and pressures than would otherwisebe possible. Normally, however, it permits the use of lower temperaturesand pressures than otherwise required. As an example of this, raw wheathaving a weight of 188 grams per unit of volume (one cup) approximately,was subjected to a series of tests. Various portions of the wheat werecooked for fifteen minutes at thirty-five pounds gauge of steampressure, in each case after removing substantially all of the air frominside the grains.

In the first group of tests, pressure was then increased to 100 poundswith steam held for fifteen seconds and the product then puffed to thefull chamber vacuum of approximately 0.2 inch of mercury absolute. Theweight of the wheat grains per cup dropped from an average of 188.5grams (average of five samples) to 18.7 grams (average of five samples)The following Table I shows the weights before and after puffing of fivesamples of wheat.

TABLE I Raw Wheat Grams Grams for fifteen seconds and then the materialpuffed to the same full chamber vacuum. In this, the five originalsamples had the same average weight as before but the average weight percup after pulling, instead of being 18.7 grams was 150 grams for thefive samples.

On the other hand, wheat cooked in the same manner for the same time andthen having the pressure raised to 115 pounds with steam airfree, heldfor fifteen swonds and then puifed to atmosphere showed an average finalweight per cup of 60.1 grams for five samples as compared to the 18.7when pufi'ed to the vacuum. 115 pounds was used here in order to havethe same pressure differences as in the first one in which the poundpressure was puffed to full vacuum.

The Doyle patent, No. 2,627,221 which issued February 3, 1953, shows apufiing apparatus particularly suitable for carrying out the processesherein described. In such an apparatus a steaming chamber is providedwithin which the product may be placed. This steaming chamber isconnected by a triggered door to an expansion chamber. The expansionchamber is preferably kept at a very low pressure, means being providedto maintain a low pressure during the pufiing. The steaming chamber isprovided with evacuating means, steaming means, and usually with a purgeline through which non-condensable gases can be eliminated as Well assome condensed steam which is developed during steaming.

As an example of the process, durum wheat was introduced to the steamingchamber. Air and other non-condensable gases were removed from the wheatgrains by reducing the pressure in the steaming chamber to about 0.2inch of mercury absolute while withdrawing the generated steam, thewheat being at a temperature of not less than about 40 F. Saturatedsteam was then introduced and the pressure increased to 35 pounds gauge,and held at this point for 15 minutes to substantially completely cookthe material without loss of cellular identity. The steam pressure wasthen raised to 100 pounds per square inch gauge, held for 15 seconds,following which the wheat was fired into the expansion chamber which inthis instance was at a pressure of 0.2 inch of mercury absolute. Thisfiring is done by suddenly releasing the triggered door of the expansionchamber and the resulting explosion ejects the wheat into the expansionchamber. The potentiometer indicated a temperature at the moment of thepuff of slightly below 32 F. indicating an actual super-cooling of thematerial. This was done by opening the triggered door of the p uningapparatus and firing the wheat into the expansion chamber. The pressurewithin the expansion chamber was maintained at a low point by continuingthe evacuation during the pumng and normally the pressure in thatchamber was not permitted to exceed 4 inches of mercury absolute andpreferably not permitted to exceed 2 inches of mercury absolute. In someinstances, however, I have operated successfully with the pressure inthe expansion chamber following the explosion riding up to as high as 4to 8 inches of mercury absolute as measured on a standrad mercurymanometer, but in most instances the pressure was reduced below 4 inchesof mercury absolute within a few minutes and before reimposition ofatmospheric pressure.

The actual values of the variables in the cooking-pufling-cyclesofthis-method:dependjuponithe condition and type of wheat. being used,aswell asthe degree-.ofpufimgdesiredz; T

The wheat grains in their normal dry state may be employed.withoutmoistening. However, inv some: instances, it maybe desiredztosupply flavor, and/or moistening, and/or nutritional values to, thegrain, prior to, during, or after pu-inng. This may-be; doneby-theuse:of a liquid carrier;. such waten; under. highptemperature and. pressurewhich is exploded into the. vessel maintaining the product under highvacuum in an atmosphere-of: steam. Byusing water under a pressure andtemperature corresponding to that, of; say, we pounds gauge of steam,theparticles.

- may be exploded into a. fine mist which will. penetrate the grains,particularly after; they have been puffed. In this way moisture, sugar,salt, certain vitamins, and nutritional. salts may be supplied to thematerial with or without other flavoring agents. This may be.done-immediately following the initial evacuation (i. e., duringcooking) or immediately following thepufling. It is, less economical todo it at some intermediate stage.

The wheat should be thoroughly cooked, for desirable pulling. I havefound that cooking at from about 35 to 100 pounds-steam pressure gaugefor a period of from about 1 /2 to l5 minutes produces satisfactoryresults. Following, cooking in the steaming chamber, the steam pressurewas adjusted to from about. 50 to 100 pounds gauge, after which thepressure was then immediately reduced to sub-atmospheric, preferablybelow 8 inches of mercury absolute and particularly to about.v 0.2.inch, of; mercuryabsolute.

The resulting vacuum puffedwheat has a volume of from about 4, to 10times the original grains. as determined by their cup weights. Putconversely, the specific. gravity as determined by cup weights is fromabout 10% to of, the specific gravity of the originalwheat grains. Thevacuum pufied, wheat particles are everted, substantially pure whiteexcept for the-brarr particles adhering thereto, and are entirelyclinkerent inshape from the original wheat grains. The cellularstructure is vitreous in appearance. On cross-section, the puffed.grains have a large number of relatively large cavities substantiallyuniformly distributed throughout the These cavities While by no-rneansspherical are generally rounded at their protuberances;

The vacuum puffed-wheat grains are immediately. wettahle by water,except in those portionsprotected by the bran fragments and whenimmersed in water at 65 F., for a period of 10 minutes, they-retaintheir entity and shape and do not break down even when mashed on amicroscopic slide.

Examplesof applying the method-of this invention are:

Emmple 1- Red durum wheat was placed in a steamchamher which was thenevacuated to an absolute pressure of about 0.2 inch of mercury absolute,the temperature of the wheat being not less than about 4.0 E, to removesubstantially all of the.

interior.

sionchamber was, continued during the. pufi until the grains were coldset.

Example 2 Red durum wheat (15 pounds) was placed in the. steam chamberand the pressure reduced to about 0.2 inchoi' mercury absolute for 2minutes, the wheatbeing at atemperature'of not: less than 40 F., toremove substantially all of the noncondensable gases. The wheat was thensteamed to a pressure of'lOO pounds per square inch gauge, held therefor 2' minutes accompanied by continualpurging of the steam, and thenfired into the expansion chamber which was at a pressure of 0.12 inch ofmercury absolute. Evacuation. of the.- expansion chamber was continuedduring the puif until. the grains were cold set.

Example 3 Red durum wheat; (5 pounds) was: placed in the steam chamberand the pressure reduced to 0.2. inch of. mercury absolute for 2minutes; the wheat being at a temperature-not less than about 46 FL, toremove substantially all of the noncondensable gases. The wheat Was thensteamed to 75 pounds per square inch gauge in minlite-,1 held; there;for 1 minutes accompanied. by continual purging of the steam, and thenfired into the expansion chamber which was at a pressure of 0.2 inch ofmercury absolute. Evacuation of the expansion chamber was continuedduring the puff until the grains were cold set.

Example 4 Wheat (5 pounds) was placed in the steam chamber and thepressurereduced to-0.2 inch of mercury absolute for 2 minutes, the wheatbeing at atemperature not less than 40 F., to remove substantially allof the non-condensabie gases. The-wheat was then steamed to a pressureof 75 pounds per square inch gauge, held there for a minutes accompaniedby continual purging of thesteam, and then fired into the expansionchamber which was at a pressure of 02 inch of mercury absolute.Evacuation of the expansion chamber was continued until the grains werecold set. r r

Example 5 Red durum wheat (20 pounds) was placed in the steam chamberand the pressure reduced to about 0.2 inch of mercury absolute for 2 minutes, the wheat being at a temperature not less than about 49 to removesubstantially all of the non-condensable gases. The wheat was thensteamed to a pressure of 109 pounds per square inch gauge. held therefor 5- minutes, following which the steam pressure was quickly reducedto 50 pounds per square inch gauge, and then the wheat was fired intothe expansion chamber which was at a pressure of 0.2 inch of mercuryabsolute. Evacuation of the expansion chamber Wascontinued during thepuff until the grains were coldset.

Ercamplc 6 Wheat was treated in the same manner as in Example 1exeeptthat in the step of removing the; non-condensable gases from theWheat grains priorto steaming, the period of evacuationat. 0.2 inchofmercury absolute pressure was 1' minute instead of 2 minutes.

Example 7 Wheat was treated in the same manner as in Example 1 exceptthat in the step of removing the non-condensable gases from the wheatgrains prior to steaming, the period of evacuation at 0.2 inch ofmercury absolute pressure was 5 minutes instead of 2 minutes.

Example 8 Wheat (20 pounds) was placed in the steam chamber and thepressure reduced to 0.2 inch of mercury absolute for 2 minutes, thewheat being at a temperature not less than about 40 F., to removesubstantially all of the non-condensable gases from the wheat grains.The wheat was then steamed at a pressure of 100 pounds per square inchgauge in 95 seconds, held there for 5 minutes and then fired into theexpansion chamber which was at a pressure of 0.2 inch of mercuryabsolute. The pressure in the expansion chamber was kept below 4 inchesof mercury absolute during the puff until the grains were cold set.

The puffed wheat grains from Examples 1 to 8 were very satisfactory,having the above described characteristics. Samples of the vacuum puffedwheat from the examples showed from 11% to 15% thiamine retention and78% to 87% lysine retention. A standard commercial puffed wheat showedthiamine retention and 35% lysine retention. The sample from Example 6had the 11% thiamine retention determination and that from Example 7 hadthe 15% thiamine retention determination.

The lysine retention was likewise greater for the vacuum puifed wheatproduct which had been evacuated for minutes before steaming, i. e.,Example 7.

The puffed wheat product produced by the process of this method showed51% nitrogen efficiency by a feed test compared to a negative efficiencyfor a corresponding commercially puffed wheat.

The foregoing detailed description has been given for clearness ofunderstanding only, and no unnecessary limitations should be understoodtherefrom for some modifications will be obvious to those skilled in theart.

I claim:

1. The method of pufiing wheat which comprises: freeing wheat grainsfrom air and replacing the air with an atmosphere of steam, cooking thewheat grains for a period sumcient to soften the cell walls and adaptthem for puffing, then subjecting the wheat grains to a sudden changefrom a high super-atmospheric pressure to a low sub-atmospheric pressurewhereby they are puffed.

2. The method as set forth in claim 1 in which the wheat grains arecooked under a pressure of steam of approximately 35 to 100 pounds persquare inch gauge.

3. The method as set forth in claim 1 in which the wheat grains arecooked under a pressure of steam of approximately 35 to 100 pounds persquare inch gauge, the pressure adjusted to from 50 to 100 pounds persquare inch gauge, and then instantaneously reducing the pressure byshooting the wheat grains into a low sub-atmospheric pressure wherebythey are puffed.

i. The method as set forth in claim 1 in which the wheat is cooked for aperiod of from 1 /2 to minutes at a pressure of from 35 to 100 poundsper square inch gauge.

5. The method which comprises cooking wheat in an atmosphere of steam,suddenly re- 8 ducing the pressure below 8 inches of mercury absolute topuff the wheat and then drying the pulled. wheat under thesub-atmospheric pressure.

6. The method as set forth in claim 5 in which the drying isaccomplished while supplying heat to the wheat.

"I. The method which comprises pufling Wheat by a sudden reduction inpressure in an atmosphere of steam and concluding the operation at anabsolute pressure substantially below 8 inches of mercury absolute, andthen introducing a volatile liquid at a temperature sufficiently high tohave an internal vapor pressure markedly above atmospheric, said mistcontaining additive fiavoring or nutritive ingredients, whereby theliquid explodes into a fine mist and penetrates the wheat.

8. In the puihng of wheat, the steps of heating the wheat in thepresence of moisture to produce a super-atmospheric steam pressurethereon and then pumng the product into a maintained vacuum sufficientlylow to cold set the product by evaporation of moisture from andconsequent cooling of the product and reimposing atmospheric pressureupon the product while in cold set condition.

9. The process of claim 8 in which the pumng operation is carried out asa batch process, the pumng being into a vacuum which is initially atsubstantially absolute zero pressure and which rises during the puiiingoperation to a point not above an average pressure of 4 inches ofmercury absolute.

10. The process of claim 8 in which the pufling operation is carried outas a batch process, the puffing being into a vacuum which is initiallyat substantially absolute zero pressure and which rises during thepufhng operation to a point not above an average pressure of 2 inches ofmercury absolute.

11. The method of claim 8 in which the product is dried after thepuffing operation is complete but before reimposition of atmosphericpressure.

12. The method of claim 8 in which the temperature of the product isreduced below F. before reimposition of atmospheric pressure.

13. The method of claim 8 in which the temperature of the product isreduced below 50 before reimposition of atmospheric pressure.

14. The method of claim 8 in which the temperature of the product isreduced below F. before reimposition of atmospheric pressure.

15. A cold set, vacuum puffed wheat product produced by the process setforth in claim 8.

. JOHN M. BAER.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,933,158 Bohn et a1 Oct. 31, 1933 2,246,528 Musher June 24,1941 2,261,456 Warren Nov. 4, 1941 2,278,464 Musher Apr. 7, 19422,295,116 Kellogg Sept. 18, 1942 2,358,250 Rogers Sept. 12, 19442,438,939 Ozai-Durrani Apr. 6, 1948 FOREIGN PATENTS Number Country Date494,085 Great Britain of 1937

1. THE METHOD OF PUFFING WHEAT WHICH COMPRISES: FREEING WHEAT GRAINSFROM AIR AND REPLACING THE AIR WITH AN ATMOSPHERE OF STEAM, COOKING THEWHEAT GRAINS FOR A PERIOD SUFFICIENT TO SOFTEN THE CELL WALLS AND ADAPTTHEM FOR PUFFING, THEN SUBJECTING THE WHEAT GRAINS TO A SUDDEN CHANGEFROM A HIGH SUPER-ATMOSPHERIC PRESSURE TO A LOW SUB-ATMOSPHERIC PRESSUREWHEREBY THEY ARE PUFFED.